1. Technical Field
A slurry used in a chemical mechanical polishing (abbreviated as xe2x80x98CMPxe2x80x99) process of a semiconductor manufacturing process is disclosed more specifically. A CMP Slurry is disclosed that is used for processing SiN or SiON films (abbreviated as xe2x80x98nitride filmsxe2x80x99) and that has a lower selectivity to an SiO film (abbreviated as xe2x80x98oxide filmxe2x80x99).
2. Description of the Related Art
Recently, much interest has been focused on a method for forming fine patterns in a semiconductor manufacturing processes. Accordingly, there are strong demands for a wide planarization technology to cure unevenness on chip and wafer surface.
The CMP process is one of the planarization technologies employed with lithography processes in the manufacturing of semiconductor devices. IBM developed the CMP process in late 1980""s by combining a chemical removing process and a mechanical polishing process.
Due to recent miniaturization, high density and multi-layer structures of semiconductor devices, current CMP processes adjust the polishing speed of the wafer and include chemical additives in the slurry to achieve local planarization.
In more detail, a chemically removable material is removed by using a chemical material having high reactivity and a processed material of a CMP slurry and the surface of the wafer is mechanically processed by using a fine abrasive at the same time. A liquid phase slurry is injected between the surface of the wafer and a rotating elastic pad.
The CMP process is essential to achieve a high density and high integration of a memory semiconductor over 64M and a non-memory semiconductor over 250 MHz.
The generally-used CMP slurry is an oxide CMP slurry. An oxide film is polished at least twice by this slurry as fast as a nitride film. Accordingly, using the nitride film as a stopping layer results in a polishing of the oxide film. The oxide CMP slurry has N/O (iexe2x80x94nitride to oxide) selectivity below 0.5.
However, when the nitride film is polished by using the oxide CMP slurry in a damascene metal gate process, the oxide film has a higher polishing speed than the nitride film, and thus a dishing phenomenon of the oxide film used as an interlayer dielectric layer occurs. It deteriorates in a succeeding photolithography or etching processes and makes it impossible to form a barrier nitride film according to the CMP process.
Consequently, the oxide CMP slurry cannot be used to polish the nitride film deposited on a substrate patterned with an oxide film.
Accordingly, a CMP slurry composition having nitride to oxide etching selectivity of N/O greater than 1 is disclosed, and a semiconductor device manufactured according to a CMP process using the composition is also disclosed.
A nitride CMP slurry composition is disclosed which has selectivity to a nitride film by generating a difference in a polishing speed of the nitride and oxide films, by varying pH of the slurry with phosphoric acid.